Determination of reference values for ultrasonic flow metering systems

1. A flow metering system, comprising:

a flow meter configured to measure volume of fluid flowing through the flow meter; and

a condition monitor coupled to the flow meter and configured to:

monitor a parameter of operation of the flow meter;

record values of the parameter over a predetermined time interval as recorded values;

determine reference values for the parameter based on the recorded values; and

apply the reference values to values of the parameter acquired after the predetermined time interval to validate operation of the flow metering system.

2. The system of claim 1 , wherein the condition monitor is configured to:

determine threshold values based on the reference values; and

compare the values of the parameter acquired after the predetermined time interval to the threshold values.

3. The system of claim 2 , wherein the condition monitor is configured to:

determine the threshold values based on an offset from a corresponding one of the reference values; and

determine the offset based on at least one of a predetermined tolerance value and standard deviation of the recorded values.

4. The system of claim 1 , wherein the parameter comprises one of ultrasonic transducer gain, gain span, chordal signal to noise ratio, chordal velocity, chordal velocity ratios, chordal velocity versus flow weighted mean velocity, flow profile, symmetry, cross flow, spread of chordal velocities, fluid swirl diagnostics, velocity/speed of sound, measured versus computed temperature, ultrasonic performance, ultrasonic peak switch diagnostics, and turbulence diagnostics.

5. The system of claim 1 , wherein the condition monitor is configured to determine the reference values by computing a mean of the recorded values.

6. The system of claim 1 , wherein the condition monitor is configured to compute each of the reference values as a mean of recorded values corresponding to a predetermined range of one of velocity and Reynolds number of the fluid flowing through the flow meter at a time each of the recorded values was acquired.

7. The system of claim 1 wherein the condition monitor is configured to compute the reference values by fitting a function to points derived from the recorded values.

8. A method for monitoring operation of a flow metering system, comprising:

acquiring and recording, as recorded values, by a monitoring system, values of a parameter of operation of the flow metering system during a predetermined reference initialization interval of operation of the flow metering system;

determining reference values for the parameter based on the recorded values of the parameter;

validating the operation of the flow metering system by applying the reference values to values of the parameter acquired after the reference initialization interval.

9. The method of claim 8 , further comprising selecting the parameter from a group consisting of ultrasonic transducer gain, gain span, chordal signal to noise ratio, chordal velocity, chordal velocity ratios, chordal velocity versus flow weighted mean velocity, flow profile, symmetry, cross flow, spread of chordal velocities, fluid swirl diagnostics, velocity/speed of sound, measured versus computed temperature, ultrasonic performance, ultrasonic peak switch diagnostics and turbulence diagnostics.

10. The method of claim 8 , further comprising:

determining threshold values based on the reference values; and

comparing the values of the parameter acquired after the reference initialization interval to the threshold values.

11. The method of claim 10 , further comprising:

determining the threshold values based on an offset from a corresponding one of the reference values; and

determining the offset based on at least one of a predetermined tolerance value and standard deviation of the recorded values.

12. The method of claim 8 , wherein determining the reference values comprises determining the reference values as a mean of the recorded values.

13. The method of claim 8 , wherein determining the reference values comprises computing each of the reference values as a mean of the recorded values corresponding to a predetermined range of one of velocity and Reynolds number of the fluid flowing through the flow meter at a time each of the recorded values was acquired.

14. The method of claim 8 , wherein determining the reference values comprises computing the reference values by fitting a function to points derived from the recorded values.

15. A condition monitoring system for monitoring operation of a flow metering system, comprising:

a reference initialization engine configured to:

record, as recorded values, values of a parameter of operation of the flow metering system over a predetermined initialization time interval of operation of the flow metering system;

determine reference values for the parameter based on the recorded values; and

a parameter verification engine configured to:

apply the reference values to values of the parameter acquired after the initialization time interval to validate operation of the flow metering system.

16. The system of claim 15 , wherein the parameter comprises one of ultrasonic transducer gain, gain span, chordal signal to noise ratio, chordal velocity, chordal velocity ratios, chordal velocity versus flow weighted mean velocity, flow profile, symmetry, cross flow, spread of chordal velocities, fluid swirl diagnostics, velocity/speed of sound, measured versus computed temperature, ultrasonic performance, ultrasonic peak switch diagnostics, and turbulence diagnostics.

17. The system of claim 15 wherein the reference initialization engine is configured to determine threshold values based on reference values; and the parameter verification engine is configured to compare the values of the parameter acquired after the predetermined time interval to the threshold values.

18. The system of claim 17 , wherein the reference initialization engine is configured to:

determine the threshold values based on an offset from a corresponding one of the reference values; and

determine the offset based on at least one of a predetermined tolerance value and standard deviation of the recorded values.

19. The system of claim 15 , wherein the reference initialization engine is configured to determine the reference values by computing a mean of the recorded values.

20. The system of claim 15 , wherein the reference initialization engine is configured to compute each of the reference values as a mean of the recorded values corresponding to a predetermined range of one of velocity and Reynolds number of the fluid flowing through the flow metering system at a time each of the recorded values was acquired.

21. The system of claim 15 , wherein the reference initialization engine is configured to compute the reference values by fitting a function to points derived from the recorded values.